The formation of Ni surface precipitates on natural soil materials may occur during sorption under ambient environmental conditions. In this study, we examined proton- and ligand-promoted dissolution of Ni surface precipitates on pyrophyllite, talc, gibbsite, amorphous silica, and a mixture of gibbsite and amorphous silica aged from 1 h to 2 yr, by employing an array of dissolution agents (ethylenediaminetetraacetic acid [EDTA], oxalate, acetylacetone, and HNO3). Ligand-promoted dissolution was more effective in removing Ni than the protolysis by HNO3. In all cases, as residence time increased from 1 h to 2 yr, the amount of Ni released from the precipitates decreased from 98 to 0%, indicating an increase in stability with aging time regardless of sorbent and dissolution agent. For example, as residence time increased from 1 h to 2 yr, Ni release from pyrophyllite, as a percentage of total Ni sorption, decreased from 96 to 30% and 23 to 0%, respectively, when EDTA (pH 4.0) and HNO3 (pH 6.0) were employed as dissolution agents for 14 d. Dissolution via oxalate of 1-yr-aged Ni–Al layered double hydroxide (LDH) on pyrophyllite saw 19% Ni removal, in comparison with 52% Ni release from α-Ni(OH)2 precipitates on talc, suggesting that α-Ni(OH)2 is less stable than Ni–Al LDH. The increase in stability of the Ni surface precipitates in this study with residence time was attributed to three aging mechanisms: (i) Al-for-Ni substitution in the octahedral sheets of the brucite-like hydroxide layers, (ii) Si-for-NO3 exchange in the interlayers of the precipitates, and (iii) Ostwald ripening of the precipitate phases. It appeared that the second factor, Si-for-NO3 exchange in the interlayers, was a major mechanism for the increase in stability of the precipitates.